1. Field of the Invention
This invention relates to a method for increasing the crushability characteristics of a ceramic article suitable for use in the casting and directional solidification of advanced superalloy material.
2. Description of the Prior Art
Superalloys, such as NiTaC-13 and other similar metal eutectic alloys, are cast and directionally solidified at temperatures of about 1700.degree. C and above for upwards of 30 hours exposure thereto. Therefore, cores and molds employed therewith must have high temperature strength and nonreactivity with the molten metal. That is, the mold and core material must not dissolve in the cast molten metal nor form an excessively thick interface compound with the molten metal. The cores also must be compatible with the superalloy to prevent hot tearing during solidification.
It is therefore an object of this invention to provide a new and improved method for enhancing the crushability characteristics of a ceramic article employed in the casting of advanced superalloy materials.
Another object of this invention is to subject a ceramic material to thermal shock to form microcracks in the microstructure of the material to improve the crushability characteristics of the article.
A further object of this invention is to provide a structure for a ceramic article which includes a predetermined porosity content, in addition to forming the microcracks in the material to improve the crushability characteristics of the article.
Other objects of this invention will, in part, be obvious and will, in part, appear hereinafter.